As you may know the "caliber" of these two is identical - 7 mm. diameter bullet. Obviously the difference is in the powder charge behind the bullet !!! The 7 mm Rem. Mag. is considered a "long action" round and the 7mm/08 Rem. is considered a short action. The 7mm/08 Rem. is derived from the 308 Win. case, necked down to 7mm. It is a superb deer round which has a relatively easy to manage recoil. This cartridge does great with 130 gr. bullets. As a shotgunner, however, the 7mm. Rem. Mag. recoil should present no problem at all. The 7mm. Rem. Mag. and 150 gr. bullets is a super choice for medium game. For my hunting area where shots are seldom over 150 yards .... and how I hunt (tree stand or ground blind) ... a 7mm./08 Rem. in a top quality , 20" - 22" barrel rifle would be my choice.